In the triple marker screen, which pattern is characteristic of Trisomy 21?

• A. AFP and UE3 decreased; hCG and Inhibin A increased
• B. AFP decreased; UE3 decreased; hCG increased; Inhibin A increased
• C. AFP increased; UE3 increased; hCG decreased; Inhibin A decreased
• D. AFP decreased; UE3 increased; hCG decreased; Inhibin A increased

Answer: (A)

In Trisomy 21, the maternal serum pattern you look for in a screening test is lower levels of AFP and unconjugated estriol (uE3) with higher levels of hCG. That combination—low AFP, low uE3, high hCG—is the hallmark signal on the triple-marker screen. Inhibin A is not part of the triple test, but when a broader quadruple panel is used, Inhibin A is often elevated in Down syndrome as well; its presence here doesn’t contradict the core pattern and can be seen as additional information. The option that shows AFP decreased, uE3 decreased, and hCG increased aligns with the characteristic pattern for Down syndrome, making it the best match among the choices.